Conduits are used in many different applications to supply and distribute various liquids and gases. Potable water, for example, typically flows through copper tubing installed throughout residential and commercial buildings. When installing copper tubing for such applications, it is typically necessary to join a number of individual tubes together. One common method of joining copper tubes involves installing a separate end fitting between adjacent tubes. The end fitting receives an end portion of a first tube and an end portion of a second tube to form a sealed connection therebetween.
One well-known method of joining end fittings to copper tubes includes soldering the respective tube ends to opposing ends of the fitting. Soldering the tubes to the fitting, however, can be a time consuming process. Moreover, modern plumbing codes have restricted the types of solder and flux that can be used for making these soldered connections. For example, lead free solder and water soluble flux is typically encouraged, rather than lead based solder and acid based flux. However, lead free solder and water soluble flux may not be as effective in connecting the fitting to the tubes as lead based solder and acid based flux.
Another method of joining a first conduit to a second conduit involves using a press fitting between the two conduits. A typical press fitting receives an end portion of each conduit and is crimped around the end portions to mechanically engage them and form a sealed connection therebetween. A press fitting can also include an adhesive, such as an epoxy or glue, to facilitate the connection. Similar to the soldered end fitting method described above, however, the press fitting has its drawbacks. For example, the press fitting is a separate component that must be crimped to each of the adjacent conduits. Accordingly, joining a number of tubes together can be a time consuming process.
Conduits in the drilling industry have also been joined together to form extended drill pipes. Metal drill pipes, such as steel drill pipes, for example, are frequently assembled by joining multiple lengths of pipe together. To join the pipes, the end portions are upset and threaded. Upsetting the end portions increases the wall thickness and diameter to facilitate threading and provide a stronger connection between the pipes. In some instances, the thickened end portions can also be welded to enhance the connection between the pipes.